源代码：

//+------------------------+

//| pie3dfun.PHP//公用函数 |

//+------------------------+

define("ANGLE_STEP", 5); //定义画椭圆弧时的角度步长

function draw_getdarkcolor($img,$clr) //求$clr对应的暗色

{

$rgb = imagecolorsforindex($img,$clr);

return array($rgb["red"]/2,$rgb["green"]/2,$rgb["blue"]/2);

}

function draw_getexy($a, $b, $d) //求角度$d对应的椭圆上的点坐标

{

$d = deg2rad($d);

return array(round($a*Cos($d)), round($b*Sin($d)));

}

function draw_arc($img,$ox,$oy,$a,$b,$sd,$ed,$clr) //椭圆弧函数

{

$n = ceil(($ed-$sd)/ANGLE_STEP);

$d = $sd;

list($x0,$y0) = draw_getexy($a,$b,$d);

for($i=0; $i<$n; $i++)

{

$d = ($d+ANGLE_STEP)>$ed?$ed:($d+ANGLE_STEP);

list($x, $y) = draw_getexy($a, $b, $d);

imageline($img, $x0+$ox, $y0+$oy, $x+$ox, $y+$oy, $clr);

$x0 = $x;

$y0 = $y;

}

}

function draw_sector($img, $ox, $oy, $a, $b, $sd, $ed, $clr) //画扇面

{

$n = ceil(($ed-$sd)/ANGLE_STEP);

$d = $sd;

list($x0,$y0) = draw_getexy($a, $b, $d);

imageline($img, $x0+$ox, $y0+$oy, $ox, $oy, $clr);

for($i=0; $i<$n; $i++)

{

$d = ($d+ANGLE_STEP)>$ed?$ed:($d+ANGLE_STEP);

list($x, $y) = draw_getexy($a, $b, $d);

imageline($img, $x0+$ox, $y0+$oy, $x+$ox, $y+$oy, $clr);

$x0 = $x;

$y0 = $y;

}

imageline($img, $x0+$ox, $y0+$oy, $ox, $oy, $clr);

list($x, $y) = draw_getexy($a/2, $b/2, ($d+$sd)/2);

imagefill($img, $x+$ox, $y+$oy, $clr);

}